Throttle actuating mechanism



Ju'i'y 1, 1958 v.\P. BIRCH 2,841,371

THROTTLE ACTUATING MECHANISM Filed Aug. s, 195e 2 sheets-sheet 1 BY @fw ATTORNEY .Bry Il, 1958 v. P. BIRCH 2,841,371

THROTTLE ACTUATING MECHANISM Filed Aug. 8, 1956 2 Sheets-Sheet 2 INVENTOR BY KFM ATTORNEY llnite tates dl'l Patented July 1, 1958 Motors Corporation, Detroit, Mich., a corp-ort' on oi We' ware Appiication August S, i956, Seria?. No. tlli 7 Claims. (Cl. E61- 23) The present invention relates to a throttle actuating mechanism for use with a carburetor of the type having a` plurality of throttles which are adapted to be sequentially operated. A carburetor of this general type is shown in copendingapplication S. N. 264,136, Olson, tiled Dece r-- ber 29, 1951, -now Patent No. 2,771,282, dated November 20, 1956.

ln carburetors of the type in which there are sequentially operating primaryl and secondary throttles, it is normal practice to provide means for locking the secondary throttle in a closed position until such time as the engine operating temperature reaches a given valueV to insure that the combustible mixture is not too lean during the time the, engine is warming up.

Ity hasV been the. practice heretofore to latch the secondary throttle in. a closed position in accordance with the position ofthe choke valve. That is to say, when the. choke is substantially closed, as is the case when the engine operating temperature is low, the secondary throttle will be maintained in a closed position. As the engine temperature increases and the choke valve isV thereafter, either manually or automatically, moved to an open position, the choke opening force will unlatch the secondary throttle permitting the latter to be opened in accordance with operator demand. The mechanisms which have heretofore accomplished this result have had at least one undesirable operating characteristic which the present invention has eliminated. In order to permit full actuation of the primary throttle when the secondary throttle is latched closed, a lost motion mechanism is provided between the throttles and which mechanism usually includes a relative heavy overtravel spring which the operator must manually overcome to full-y open the primary throttle. In the present invention a unique linkagey mechanism is provided which eliminates the overtravel spring and its accompanying` resistance to primary throttle actuation.

Inv the present invention, the position 0I" the choke still determines whether or not the operative. connection between the secondary and primary throttles is to be interrupted; however, the. actual force utilized in effectingV a change in the operative connection is supplied by the opening and closing movement of the primary throttles as dictated by the operators actuation of the. vehicle accelerator pedal.

Accordingly, the present invention provides a sequential throttle operating device which enables throttle actuation to be achieved with a considerably reduced elfort on the part of the operator aswell as reducing` loadon the accelerator pedal-to-throttle linkage mechanism. In both respects, these improved results. also contirbute to asimpler and more economically: manufactured throttle actuating mechanism.

Additional objects and advantagesv of the present invention will be realized from a perusal of the detailed description which follows.

In the. drawings:

Figure l shows a carburetor embodying the subject throttle actuating mechanism. a

Figure 2 is a fragmentary view of Figure 1 1n which part of the throttle actuating mechanism has been elimi nated to better illustrate details.

Figure 3V shows an exploded perspective view of the throttle actuating mechanism.

While it is applicable to any carburetor utilizing sequentially operating throttles, the invention is shown in the environment of a four-barrel carburetor of the. type shown andA described in detail in copending application S. N. 264,136, Olson et al., led December 29, 1951, now Patent No. 2,771,282, issued November 20, 1956. The subject carburetor, except as hereinafter specifically` de.- scribed functions in the same manner as in the aforementioned carburetor copending application and a de tailed description thereof will not be made.

Referring to Figure 1, the carburetor is shown generally at l@ and includes a float bowl casing 12, a oat bowl casing cover 14 and a throttle body 16. Disposed within the cover i4 isa choke valve 17 adapted to control the llow of air through the primary inductionV pas.- sages 18 Also, disposed in the primary induction passage posteriorly of the choke valve is a pair of primary throttles 20 which are pivotally mounted in the throttle body 16 upon a shaft 22. A secondary or auxiliary induction passage is shown generally at 24 and includes a pair of throttle valves 26 tired to shaft 28 for rotation therewith.

Choke valve 17' is of the automatic type andis offset with respect, to its shaft 30. so as to beresponsive to the iiow of air therepast. Further, choke valve 17 is automatically controlled in accordance with engine temperature and manifold vacuum through a device of theY type shown and described in the aforementioned copending application. The operation of the automatic choke is Such that whenY the engine operating temperature is low the thermostat maintains the choke in a closed position gradually permitting the choke to open under the influence of manifold vacuum and air ow as the engine temperature increases.

A throttle operatingv lever 32 is xed to the primary throttle shaft 22 and includes an arm 34 adapted to be suitably articulated at one end to a throttle rod 36 which is controlled by the accelerator pedal in such a way that as the accelerator pedal is depressed the throttle rod 36 rotates the lever 32 in a clockwise directionV to open the primary throttles 255. Arm S4 of lever 32 is offset and has a tab 3S adapted to threadably receive an idle ad,- justing screw 40 which is adapted to coact with a fast idle cam 42 pivotally mounted upon the throttle body 16 through a stud 44. The fast idle cam 42.Y is connectedinterrnediate its ends to one end of a link 46, the other end of which link is pivotally connected to the choke shaft 3@ through a suitable lever 4S.

As the choke valve opens, the fast idle cam is rotated in a counterclockwise direction permitting the idle adjusting screw to engage with the progressively lower steps on the earn periphery as the engine warms up and higher idling speeds, become unnecessary. The fast idle cam also includes` a deloading tang Si? which is adapted to be enaged by an oiset arm 52 projecting from lever 32. The arm is adapted, when the throttle is moved to a wide open position, to engage tang 5i) and thereby positively open the choke valve 17 to unload the primaryinduction passage to atmosphere.

Mounted on theprimary throttle shaft 22 is a lever 54 which is adapted to be moved axially as well as rotarily' relative thereto. Lever 54 includes arms 56 andV 58.

Ann 56 is pivotally connected at one end to a link 60, the other end or which is pivotally connected to a sec- Vopening ofY the primary throttles willrhave kthe opening Vof ythe secondary .throttles A As engine temperature increases to a point where the ondary throtde actuating lever`62. Lever 62 is xed Y Vto the secondary throttle shaft 28.

n* YPrimary throttle actuatinglever 32 has. a tang orfprojection 66' extending therefronrwhich is adapted uponY power demand. i

In order to insure, however, even when the Yoperator moves the primary throttle to the point where secondary throttle operation would normally begin, that such sec-V Y ondary-throttle actuation does not take place due to low Y engine temperature, it is necessary to provide a means for rendering the secondary throttle inoperative. To this end a YYmember 70 is providedwhich is pivotally'supported at one end to choke link 46.". The other end of member 70 is hifurcated so as to provide an open-ended slot-71 which is adapted to surround and be supported Aupon the' primary throttle shaft 22. Member 70'is supported by shaft 22 and link 46 in such a way as to be axially movable withY respect thereto. Intermediate the ends of member 70 there isan'upstruck cam surface 72 Awhich projects in the direction of thelprimary throttle lever 32.` In the position asshown'in and which follower is adapted to coact with cam surface 72 ina manner to be'hereinafter described. Y Y

A spring78 is mounted on the primary throttle shaft 22 Yand seatsjagainst aV shoulder 80 to urge lever 54 and 'member 70V axially into juxtaposition relative to the primary throttle lever 32. v With the choke valve 17 closed the choke linkY 46 will maintain the right end of member 70 in a raisedposition Vin which thercam follower member or tang 74-of lever,V

32 is in alignment` with Ythe Vcam surface 72 and disposed immediately thereabove'. Thereafter, as the primar", throttle lever'is rotated in ar clockwise direction to open the primary throttle, the follower member74 will engage the cam surface .72, as seen in Figure 1, forcing member 70 and abutting lever 54 4axially'awayrfrorn the primary throttle lever against the forcerof spring 78. l In so doing, arm 56 Yof lever 54 is moved axially outY of theV range of Contact by tang 66 `on lever 32. Thus, the rotation of the primary throttle causes a portion of the linkage mechanism connecting the primary and secondaryrthrob tles to be shifted to a neutral position such that further no elect on chokevalvecan be opened to reduce the richnessfof the operatingmixture, theV choke link v46 will move down- Wardly, under the forceA of gravity, moving the ,right end of member 70" downwardly and thereby causing the cam surface72 to moved to a non-cooperating position with respect to the cam follower tang 74 on the primary throttle lever .32.V Thus, with the engine sufficiently warm, rotation of the primary throttle to the aforementioned V40" position will cause tang66 to engage arm 56 of lever v 54 rotating the latter in a clockwise direction and thereby imparting aV counterclockwise movement to secondary throttle lever 62 which opens the secondary throttles 26. t The secondaryY throttle shaft has coiledjthere'about a torsion spring S4 which tends to urge the secondary throttlestoward a closed position. 'Y jV With the mechanism provided by applicant the operator in'movingthe throttle from a'closed to an open position experiences a substantially continuous and essentially light reaction to throttlepedal movement in contradistinction to the previous devices in which a heavy resistance had to be overcome when the secondary throttles were ren- Y h Figure 3, there is Vanjupstruck portion or follower 7'4. formed on lever32 Y least one of Vsaid shafts to disconnect the Y ment.

4 dered inoperative becauserof nsucient engine operating temperatures.

I claim: Y

l. A carburetor comprising rst and second induction passages, throttle valves for respectively controlling the Aflow through said induction passages, a mechanism for 2. A carburetor comprising first and second induction '.1 passages, a shaft extending transversely through each of said induction passages, throttle valves mounted oneach of said shafts for respectively controlling the flow through the associated passage, a linkagedevice for operatively connecting said first andsecond throttles for sequential operation, temperature responsive kmeans Vconnected to(V said device' and adapted when-the engine temperature is low, to move a portion of said device to a position in which the opening movement of said rst throttle shifts a portion of said linkage device axiallyrelative to at operative connection between said throttles. Y 3. A carburetor including iirst and second induction passages, a throttle valve mounted on a ,shaft in Veach passage to control'ow therethrough, first and secondk levers respectively fixed to said-throttlershaftsrfor rotation therewith, means for controlling the actuation of one of said levers, a third lever mounted for axial movement on the rstinduction passagethrottle shaft'and engageableV by the irst lever, a link between saidv second and V'third levers, a thermostatically controlled', element disposed intermediate said iirstand thirdY levers, sairdvelement being movable to a position when engine temperature is low in which the element is engageable bythe first lever duringropen movement toshift the thirdlever axially out of engagement with the iii-,st lever', and means biasing said first and third levers into operative engage- 4. A carburetor having primary and lsecondary induc-V tion passages, `a throttle valve pivotally'niou'nted on a shaft in each passage to ycontrol the flow ofpar therethrough, a temperature responsive choke mounted in the primary induction passage anteriorly of the throttle valve, linkage means connecting'saidV throttle valves for sequential operation, said means includingiirstand second levers respectively xed tothe primary andY secondary throttle shafts,` a pair'of elements supportedpuponpthe primaryrshaftrfor axial andj rotary movement relativeY theretojmean's biasing said elements axiallyinto operative engagement with the first lever, one of said Yelements being articulated toV saidY` secondelever whereby VVrotary movementof the primary throttle shaft maymbe transmined t@ the secondary throttle Shaft, the` other, of `said elements being articulated to said choke, the choke controlled element being movable to a position whenengine Y 'Y temperature is low in whichthe rotary opening movement of the'rst lever will shift the-elements axiallyY to interrupt the operative connection between said Athrottle valves.V v Y Y' 5. A carburetor having primary and secondary induction passages, a `throttle valve pivotallyrrmounterd 'onja shaft in each passage to control theowrof airztherethrough, a choke valve mounted inthe primary induction passage anteriorly of the vthrottle valve, linkage means connecting said throttle valves Yfor'rserquentialoperation,

` said means includingzrst and second levers respectively ixed to the primary and secondaryV throttleV shafts, a pair 'Y of elements supported upon the primary'shaft for axial and rotary movement relative thereto, means biasing said 53 elements axially into operative engagement with the irst lever, one of said elements being articulated to said second lever and the other element to said choke whereby rotary movement of the primary throttle shaft may be transmitted to the secondary throttle shaft, said choke controlled element having a cam surface thereon, said first lever including a portion adapted to engage said cam surface when said choke valve is in a substantially closed position enabling rotation of said first lever to `shift said elements axially to interrupt the operative connection between said throttle valves.

6. A carburetor comprising primary and secondary induction passages; throttle valves mounted on shafts in said passages to control flow therethrough; a choke valve disposed in said primary passage anteriorly of the throttle; a linkage mechanism operatively connecting said thorttles for sequential operation, and a device operated by said choke valve which causes the opening movement of the primary throttle to disconnect the operative connection between said throttles when the choke is in a substantially closed position permitting the primary throttie to open without opening the secondary throttle.

7. A carburetor including first and second induction passages, a throttle valve mounted on a shaft in each passage to control rlow therethrough, first and second levers respectively iiXed to said throttle shafts for rotation therewith, means for controlling the actuation of one of said levers, a third lever mounted for axial movement on the rst induction passage throttle shaft and engageable by the rst lever, a rigid link articulated between said second and third levers, an element movable to a position in which it is engaged by the opening movement of said rst lever to shift the third lever axially out of engagement with the first lever, and means normally biasing said iirst and third levers into operative engagement.

References Cited in the iile of this patent UNITED STATES PATENTS Carlson et al Aug. 16, 1955 

